JP2549709B2 - Rear-wheel steering system for 4-wheel steering vehicle - Google Patents
Rear-wheel steering system for 4-wheel steering vehicleInfo
- Publication number
- JP2549709B2 JP2549709B2 JP63165935A JP16593588A JP2549709B2 JP 2549709 B2 JP2549709 B2 JP 2549709B2 JP 63165935 A JP63165935 A JP 63165935A JP 16593588 A JP16593588 A JP 16593588A JP 2549709 B2 JP2549709 B2 JP 2549709B2
- Authority
- JP
- Japan
- Prior art keywords
- steering
- angular velocity
- wheel steering
- rear wheel
- yaw rate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は車両の後輪を操舵する後輪操舵装置に関する
ものである。Description: TECHNICAL FIELD The present invention relates to a rear wheel steering device that steers the rear wheels of a vehicle.
（従来の技術） 後輪操舵技術としては従来特開昭60−229873号公報に
記載の如く、前輪操舵時操舵角θ及び操舵角速度に夫
々比例定数Ｋ及び微分定数τ（k,τは正の値）を乗じて
求まる舵角δｒ＝Ｋ・θ−τ・だけ後輪を操舵して、
操舵周波数に対するヨーレイトゲイン特性がフラットに
なるよう、つまり操舵速度に関係なく操舵角θに比例し
て位相遅れなしにヨーレイトが発生するようになす技術
が知られている。(Prior Art) As a rear wheel steering technique, as described in Japanese Patent Application Laid-Open No. 60-229873, a proportional constant K and a differential constant τ (k and τ are positive with respect to a steering angle θ and a steering angular velocity during front wheel steering, respectively. Steering angle δ r = K · θ−τ · steered by the rear wheel
A technique is known in which the yaw rate gain characteristic with respect to the steering frequency is flat, that is, the yaw rate is generated in proportion to the steering angle θ without phase delay regardless of the steering speed.
この場合、比例定数ｋ及び微分定数τは夫々車両毎に
又社速に応じて異なり、例えば車両の質量Ｍが160kgS2/
m、ヨー慣性モーメントＩが252kgS2、ホイールベースｌ
が2.48mの車両をＶ＝120km/hで走行させる場合、K,τは
夫々0.38,−0.049であり、Ｍ＝125kgS2/m、Ｉ＝227kg
S2、ｌ＝2.48mの車両を同じＶ＝120km/hで走行させる場
合、K,τは夫々0.33、−0.056である。In this case, the proportional constant k and the differential constant τ are different for each vehicle and according to the company speed, for example, the mass M of the vehicle is 160 kgS 2 /
m, yaw moment of inertia I is 252kgS 2 , wheel base l
When driving a vehicle of 2.48 m at V = 120 km / h, K and τ are 0.38 and −0.049, respectively, M = 125 kgS 2 / m, I = 227 kg
When a vehicle with S 2 and l = 2.48 m is run at the same V = 120 km / h, K and τ are 0.33 and −0.056, respectively.
このように定めた比例定数及び微分定数から前記の式
により求まる舵角δｒだけ後輪を操舵する場合、この後
輪舵角δｒにより上記操舵条件の場合、操舵周波数に対
するヨーレイトゲイン／θの変化を所望のフラットな
ものとすることができる。When the rear wheels are steered by the steering angle δ r obtained by the above formula from the proportional constant and the differential constant determined in this way, in the case of the above steering conditions by the rear wheel steering angle δ r , the yaw rate gain / θ with respect to the steering frequency is The change can be as flat as desired.
（発明が解決しようとする課題） しかしながらこの後輪操舵技術においては上記効果を
得られる反面、ヨーレイトの操舵周波数応答特性が高周
波域では２輪操舵（2WS）車両より位相遅れが減少して
向上するものの、低周波域では2WS車両より位相遅れが
大きくなってしまうという問題があった。すなわち上述
のようにして求めた最適値の比例定数Ｋ及び微分定数τ
を用いた位相反転制御を行う従来の後輪技術によるヨー
レイトの操舵周波数応答特性は第４図（ｂ）の実線に示
すようになり、点線で示す2WSの場合の操舵周波数応答
特性と比較すると約１（Hz）以下においては2WSより劣
るものとなってしまう（なお、比例制御δｒ＝Ｋ・θの
場合を一点鎖線で示す）。この理由は後輪舵角δｒ（δ
ｒ＝Ｋ・θ−τ・）の同相要素Ｋ・θが増えるとヨー
レイト位相遅れが2WSより大きくなり、逆相要素τ・
が増えるとヨーレイト位相遅れが2WSより小さくなるか
ら、操舵周波数の低周波域、すなわちステアリングをゆ
っくりと操作した場合（小）には同相要素Ｋ・θが変
わらなくても逆相要素τ・が減少して相対的に同相傾
向が強まり、位相が2WSより遅れるからである。(Problems to be Solved by the Invention) However, in the rear wheel steering technique, the above effect can be obtained, but on the other hand, the steering frequency response characteristic of the yaw rate is improved in the high frequency range by reducing the phase delay as compared with the two wheel steering (2WS) vehicle. However, there was a problem that the phase delay was larger than that of the 2WS vehicle in the low frequency range. That is, the proportional constant K and the differential constant τ of the optimum values obtained as described above.
The steering frequency response characteristic of the yaw rate by the conventional rear wheel technology that performs phase inversion control using is as shown by the solid line in Fig. 4 (b). Compared with the steering frequency response characteristic of 2WS shown by the dotted line, it is about Below 1 (Hz), it is inferior to 2WS (note that the case of proportional control δ r = K · θ is shown by the one-dot chain line). The reason for this is that the rear wheel steering angle δ r (δ
When the in -phase element K · θ of r = K · θ−τ ·) increases, the yaw rate phase delay becomes larger than 2WS, and the anti-phase element τ ·
, The yaw rate phase delay becomes smaller than 2WS. Therefore, in the low frequency range of the steering frequency, that is, when the steering is operated slowly (small), the anti-phase element τ ・ decreases even if the in-phase element K ・ θ does not change. This is because the in-phase tendency becomes relatively stronger and the phase lags behind 2WS.
（課題を解決するための手段） 本発明は微分定数を操舵条件に応じて可変にすること
により上述した問題を解決しようとするもので、前輪操
舵時、操舵角に比例定数を乗じて求まる同相要素および
操舵角速度に微分定数を乗じて求まる逆相要素を含む舵
角に応じて後輪を操舵する後輪操舵装置において、 操舵角速度が所定値以下のときの微分定数を、操舵角
速度が前記所定値を超えるときに設定した微分定数に対
し、操舵角速度の減少に応じて増加させるように構成し
たことを特徴とする。(Means for Solving the Problem) The present invention is intended to solve the above-mentioned problem by making the differential constant variable according to the steering condition. During the front wheel steering, the steering angle is obtained by multiplying the steering angle by a proportional constant. In a rear wheel steering device that steers the rear wheels according to a steering angle that includes an antiphase element that is obtained by multiplying the element and the steering angular velocity by a differential constant, the steering wheel angular velocity is the differential constant when the steering angular velocity is a predetermined value or less. It is characterized in that the differential constant set when the value exceeds the value is increased according to the decrease of the steering angular velocity.
（作 用） 車両の旋回走行時前輪操舵に応じて後輪も所定の後輪
舵角で操舵される。この後輪舵角の逆相要素は前輪の操
舵角速度及び微分定数により決定される。(Operation) When the vehicle is turning, the rear wheels are also steered at a predetermined rear wheel steering angle according to the front wheel steering. The antiphase element of the rear wheel steering angle is determined by the steering angular velocity of the front wheels and the differential constant.
ここで操舵周波数と操舵角速度とはほぼ比例するもの
と考え、操舵角速度が所定値を超える操舵周波数の高周
波域では前記微分定数に対して補正を行わず、設定値
（最適値）のままとする。なおこの設定値は固定値と
し、前記文献に記載のように、操舵周波数に対するヨー
レイトゲイン（／θ）の変化をフラットにするととも
に高周波域におけるヨーレイト位相遅れを改善するもの
とする。Here, it is considered that the steering frequency and the steering angular velocity are substantially proportional to each other, and in the high frequency region of the steering frequency at which the steering angular velocity exceeds a predetermined value, the differential constant is not corrected and remains at the set value (optimal value). . Note that this set value is a fixed value, and as described in the above-mentioned document, the change of the yaw rate gain (/ θ) with respect to the steering frequency is made flat and the yaw rate phase delay in the high frequency range is improved.
一方操舵角速度が所定値以下になる操舵周波数の低周
波域では、前記微分定数を上述した高周波域の設定値に
対し操舵角速度の減少に応じて増加させた設定値とする
から、操舵周波数の低周波域におけるヨーレイト位相遅
れを従来の装置より大幅に改善することができる。On the other hand, in the low frequency region of the steering frequency where the steering angular velocity is equal to or lower than the predetermined value, the differential constant is set to a value that is increased in accordance with the decrease of the steering angular velocity with respect to the set value of the high frequency region described above. The yaw rate phase delay in the frequency range can be greatly improved as compared with the conventional device.
このようにして微分定数を操舵条件に応じて可変にす
ることにより、高周波域のヨーレイトの操舵周波数特性
を悪化させることなく低周波域のヨーレイトの位相遅れ
を改善することができるから、操舵周波数の全域に亘っ
てヨーレイトの操舵周波数応答特性を好適にすることが
できる。By making the differential constant variable according to the steering condition in this way, the phase delay of the yaw rate in the low frequency range can be improved without deteriorating the steering frequency characteristic of the yaw rate in the high frequency range. The yaw rate steering frequency response characteristic can be made favorable over the entire region.
（実施例） 以下、本発明の実施例を図面に基づき詳細に説明す
る。(Example) Hereinafter, the Example of this invention is described in detail based on drawing.
第１図は本発明後輪操舵装置を搭載した４輪操舵車両
の全体構成を示し、図中1L,1Rは夫々左右前輪、2L,2Rは
左右後輪、３はステアリングホイールである。前輪1L,1
Rは夫々ステアリングホイール３によりステアリングギ
ヤ４を介して転舵可能とし、後輪2L,2Rは夫々後輪転舵
アクチュエータ５により転舵可能とする。FIG. 1 shows the overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering system of the present invention. In the figure, 1L and 1R are left and right front wheels, 2L and 2R are left and right rear wheels, and 3 is a steering wheel. Front wheel 1L, 1
R can be steered by the steering wheel 3 via the steering gear 4, and the rear wheels 2L, 2R can be steered by the rear wheel steering actuators 5, respectively.
アクチュエータ５はスプリングセンタ式油圧アクチュ
エータとし、室5Rに油圧を供給する時圧力に比例した舵
角だけ後輪2L,2Rを夫々右に転舵し、室5Lに油圧を供給
する時圧力に比例した舵角だけ後輪2L,2Rを夫々左に転
舵するものとする。The actuator 5 is a spring center type hydraulic actuator, and the rear wheels 2L and 2R are each steered to the right by a steering angle proportional to the pressure when the hydraulic pressure is supplied to the chamber 5R, and is proportional to the pressure when the hydraulic pressure is supplied to the chamber 5L. It is assumed that the rear wheels 2L and 2R are steered to the left by the steering angle.
アクチュエータ室5L,5Rへの油圧を制御する電磁比例
式後輪転舵制御弁６を設け、この弁６は可変絞り6a,6b,
6c,6dをブリッジ接続して具え、このブリッジ回路にポ
ンプ７、リザーバ８及びアクチュエータ室5L,5Rからの
油路9,10を夫々接続する。弁６は更にソレノイド6L,6R
を具え、これらのソレノイドはOFF時夫々可変絞り6a,6b
及び6c,6dを全開させて両アクチュエータ室5L,5Rを無圧
状態にし、ソレノイド6L又は6Rの電流値IL又はIRによる
ON時可変絞り6c,6d又は6a,6bを電流値に応じた開度に絞
ってアクチュエータ室5L又は5Rに電流値IL又はIRに応じ
た油圧を供給するものとする。その油圧は前記したよう
にその値に応じた角度だけ後輪を対応方向へ転舵する。An electromagnetic proportional rear wheel steering control valve 6 for controlling the hydraulic pressure to the actuator chambers 5L, 5R is provided, and the valve 6 is provided with variable throttles 6a, 6b,
6c and 6d are connected in a bridge, and the pump 7, the reservoir 8, and the oil passages 9 and 10 from the actuator chambers 5L and 5R are connected to the bridge circuit, respectively. Valve 6 also has solenoids 6L and 6R
These solenoids have variable throttles 6a and 6b respectively when they are turned off.
And 6c, 6d are fully opened to make both actuator chambers 5L, 5R non-pressurized, depending on the current value I L or I R of the solenoid 6L or 6R.
And supplies ON when the variable diaphragm 6c, 6d or 6a, the oil pressure corresponding to the current value I L or I R to an actuator chamber 5L or 5R squeezed 6b to the opening degree corresponding to the current value. As described above, the hydraulic pressure steers the rear wheels in the corresponding direction by an angle corresponding to the value.
ソレノイド6L,6Rの駆動電流IL,IRをコントローラ11に
より制御し、このコントローラにはステアリングホイー
ル操舵角θを検出する操舵角センサ12からの信号及び車
速Ｖを検出する車速センサ13からの信号を夫々入力す
る。コントローラ11はこれら入力情報を基に第２図の如
くに機能して後輪操舵を行うものとする。The controller 11 controls the drive currents I L and I R of the solenoids 6L and 6R, and this controller outputs a signal from the steering angle sensor 12 that detects the steering wheel steering angle θ and a signal from the vehicle speed sensor 13 that detects the vehicle speed V. Respectively. Based on these input information, the controller 11 functions as shown in FIG. 2 to perform rear wheel steering.
すなわちステップ101で操舵角θ及び車速Ｖを読込
み、ステップ102で前記操舵角θより操舵角速度をコ
ントローラ11の内部演算により求め、ステップ103で前
記車速Ｖ及び操舵角速度に基づき比例定数Ｋ及び微分
定数τをテーブルルックアップする。なお内部演算方法
は、今回のサイクルの操舵角θとＫ回前のサイクルの操
舵角θＫとの差を時間Δｔ×Ｋで除して操舵角速度を
求める（＝θ−θK/Δｔ×ｋ）ものとする。That is, the steering angle θ and the vehicle speed V are read in step 101, the steering angular velocity is obtained from the steering angle θ by an internal calculation of the controller 11 in step 102, and the proportional constant K and the differential constant τ are calculated in step 103 based on the vehicle speed V and the steering angular velocity. Look up the table. The internal calculation method is to find the steering angular velocity by dividing the difference between the steering angle θ of the present cycle and the steering angle θ K of the cycle K times before by the time Δt × K (= θ−θ K / Δt × k ).
これら定数K,τは操舵周波数に対するヨーレイトゲイ
ン特性をフラットにするものとし、さらに微分定数τは
ヨーレイトの位相遅れ特性を操舵周波数の高周波域で2W
Sより改善するのは勿論、低周波域でも2WS並に改善する
ものとする。These constants K and τ are used to flatten the yaw rate gain characteristic with respect to the steering frequency, and the differential constant τ shows the phase delay characteristic of the yaw rate at 2 W in the high frequency range of the steering frequency.
Of course, it will be improved from S, and it will be improved to the level of 2WS in the low frequency range.
この微分定数τを、所定車速毎に用意された複数のマ
ップ（そのパターンの一例を第３図に示す）の内の選択
されたマップにおいて、操舵角速度が所定値（本例で
は40deg/secであり、この値は前述した約1Hzに対応す
る）を超えるときτ＝τ０（最適値）とし、操舵角速度
が前記所定値以下のときτ＝τ０＋Δτとしてその操
舵角速度に応じた補正を加える。この補正値Δτ（０
＜Δτ≦τ１−τ０）は操舵角速度が小さいほど大き
な値となり＝０のとき（τ１−τ０）となるもので、
車速が低くなるほど補正値の最大値は小さくなる。This differential constant τ is calculated by selecting the steering angular velocity at a predetermined value (40 deg / sec in this example) in a map selected from a plurality of maps prepared for each predetermined vehicle speed (an example of the pattern is shown in FIG. 3). Yes, this value corresponds to about 1 Hz described above), and τ = τ 0 (optimum value), and when the steering angular velocity is less than or equal to the predetermined value, τ = τ 0 + Δτ and the correction according to the steering angular velocity is added. . This correction value Δτ (0
<Δτ ≦ τ 1 −τ 0 ) has a larger value as the steering angular velocity is smaller and becomes (τ 1 −τ 0 ) when = 0,
The lower the vehicle speed, the smaller the maximum correction value.
次のステップ104で上記比例定数Ｋ及び微分定数τ
と、操舵角θ及び操舵角速度とから後輪舵角δｒをδ
ｒ＝Ｋ・θ−τ・の演算により求め、ステップ105,10
6でこの後輪舵角を得るためのソレノイド駆動電流IR,IL
をテーブルルックアップし、ステップ107,108で制御弁
６のソレノイド6R,6Lに夫々駆動電流IR,ILを出力して後
輪をδｒだけ操舵する。In the next step 104, the proportional constant K and the differential constant τ
And the steering angle θ and the steering angular velocity, the rear wheel steering angle δ r
r = K · θ−τ · is calculated, and steps 105 and 10 are obtained.
6 Solenoid drive current I R , I L to obtain this rear wheel steering angle
Then, in steps 107 and 108, driving currents I R and I L are output to the solenoids 6R and 6L of the control valve 6 to steer the rear wheels by δ r .
上述した制御によるヨーレイト位相遅れ及びヨーレイ
トゲインの特性は、第４図（ａ）の実線で示すようにな
るから（比較のため従来例の4WS車両の特性を点線で示
す）、操舵周波数の低周波域（約1Hz以下）における位
相遅れを前述した従来の位相反転制御（4WS）より小さ
く、ほぼ2WS並に改善して、操舵周波数の全域に亘って
ヨーレイトの周波数応答特性を好適にすることができ
る。The characteristics of the yaw rate phase delay and the yaw rate gain by the control described above are shown by the solid line in FIG. 4 (a) (the characteristics of the conventional 4WS vehicle are shown by the dotted line for comparison). The phase lag in the range (about 1Hz or less) is smaller than the conventional phase reversal control (4WS) described above and improved to almost 2WS, and the yaw rate frequency response characteristic can be optimized over the entire steering frequency range. .
（発明の効果） かくして本発明４輪操舵車両の後輪操舵装置は上述の
如く、微分定数を操舵条件に応じて可変にして、操舵角
速度が所定値以下のときの微分定数を、操舵角速度が前
記所定値を超えるときに設定した微分定数に対し、操舵
角速度の減少に応じて増加させて逆相操舵量を増加させ
たから、高周波域のヨーレイトの操舵周波数特性を悪化
させることなく低周波域のヨーレイトの位相遅れを改善
するので、操舵周波数の全域に亘ってヨーレイトの操舵
周波数応答特性を好適にすることができる。(Effects of the Invention) As described above, the rear-wheel steering system for a four-wheel steering vehicle according to the present invention makes the differential constant variable according to the steering condition so that the steering angular velocity can be changed when the steering angular velocity is equal to or less than a predetermined value. With respect to the differential constant set when the predetermined value is exceeded, the antiphase steering amount is increased by increasing in accordance with the decrease in the steering angular velocity, so that the steering frequency characteristic of the yaw rate in the high frequency range is not deteriorated and Since the yaw rate phase delay is improved, the yaw rate steering frequency response characteristic can be made favorable over the entire steering frequency range.
第１図は本発明後輪操舵装置を搭載した４輪操舵車両の
全体構成を例示する線図、 第２図は同例のコントローラによる後輪舵角制御機能を
示すフローチャート、 第３図は同例の微分定数のマップの一例を示す線図、 第４図（ａ），（ｂ）は同例及び従来例のヨーレイトの
操舵周波数応答特性を示す特性図である。 1L,1R……前輪、2L,2R……後輪 ３……ステアリングホイール ４……ステアリングギヤ ５……後輪転舵アクチュエータ ６……電磁比例式後輪転舵制御弁 11……コントローラ、12……操舵角センサ 13……車速センサFIG. 1 is a diagram illustrating an overall configuration of a four-wheel steering vehicle equipped with a rear wheel steering device of the present invention, FIG. 2 is a flowchart showing a rear wheel steering angle control function by a controller of the same example, and FIG. FIG. 4A and FIG. 4B are characteristic diagrams showing the steering frequency response characteristics of the yaw rate of the same example and the conventional example, respectively. 1L, 1R …… Front wheel, 2L, 2R …… Rear wheel 3 …… Steering wheel 4 …… Steering gear 5 …… Rear wheel steering actuator 6 …… Electromagnetic proportional rear wheel steering control valve 11 …… Controller, 12 …… Steering angle sensor 13 ... Vehicle speed sensor
Claims (1)
まる同相要素および操舵角速度に微分定数を乗じて求ま
る逆相要素を含む舵角に応じて後輪を操舵する後輪操舵
装置において、 操舵角速度が所定値以下のときの微分定数を、操舵角速
度が前記所定値を超えるときに設定した微分定数に対
し、操舵角速度の減少に応じて増加させるように構成し
たことを特徴とする４輪操舵車両の後輪操舵装置。1. A rear wheel steering system for steering a rear wheel according to a steering angle, which includes an in-phase element obtained by multiplying a steering angle by a proportional constant and an anti-phase element obtained by multiplying a steering angular velocity by a differential constant during steering of front wheels. The differential constant when the steering angular velocity is equal to or less than a predetermined value is increased with respect to the differential constant set when the steering angular velocity exceeds the predetermined value in accordance with the decrease in the steering angular velocity. Rear wheel steering system for wheel steering vehicles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63165935A JP2549709B2 (en) | 1988-07-05 | 1988-07-05 | Rear-wheel steering system for 4-wheel steering vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63165935A JP2549709B2 (en) | 1988-07-05 | 1988-07-05 | Rear-wheel steering system for 4-wheel steering vehicle |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0218172A JPH0218172A (en) | 1990-01-22 |
| JP2549709B2 true JP2549709B2 (en) | 1996-10-30 |
Family
ID=15821811
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63165935A Expired - Lifetime JP2549709B2 (en) | 1988-07-05 | 1988-07-05 | Rear-wheel steering system for 4-wheel steering vehicle |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2549709B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07112826B2 (en) * | 1984-04-27 | 1995-12-06 | トヨタ自動車株式会社 | Rear-wheel steering control method for four-wheel steering vehicle |
| JPS6218367A (en) * | 1985-07-18 | 1987-01-27 | Mazda Motor Corp | Four-wheel steering gear of vehicle |
-
1988
- 1988-07-05 JP JP63165935A patent/JP2549709B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0218172A (en) | 1990-01-22 |
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